Last day I connected the Microserver Gen8 and found the light of the iLO NIC port was always off and I also could not find its ip address from the router log, while the other two host NICs worked well.
I thought maybe the iLO processor failed and tried to search any related posts on the internet, and the below one gave me the right answer:
And I fixed it through below steps:
./hponcfg -w ilo.xml
more ilo.xml --> check the content
./hponcfg -f ilo.xml
After that, when I plugged the cable into the iLO port, I could ping it.